Young-Seog Kim

Pukyong National University · Department of Earth and Environmental Sciences

The AMoRE collaboration conducts experiments to search for the neutrinoless double beta decay of \(^{100}\)Mo using massive \(\hbox {Li}_{2}\hbox {MoO}_{4}\) (LMO) crystals in a cryogenic calorimetric detection with metallic magnetic calorimeters (MMCs). The detector module incorporates a light detector with Si or Ge wafers, enabling the simultaneo...

A new 2,400 L liquid scintillator has been produced for the COSINE-100 Upgrade, which is under construction at Yemilab for the next COSINE dark matter experiment phase. The linear-alkyl-benzene-based scintillator is designed to serve as a veto for NaI(Tl) crystal targets and a separate platform for rare event searches. We measured using a sample co...

The Neutrino Elastic-scattering Observation with NaI(Tl) experiment (NEON) aims to detect coherent elastic neutrino-nucleus scattering (CEνNS) in a NaI(Tl) crystal using reactor anti-electron neutrinos at the Hanbit nuclear power plant complex. A total of 13.3 kg of NaI(Tl) crystals were initially installed in December 2020 at the tendon gallery, 2...

An upgrade of the COSINE-100 experiment, COSINE-100U, has been prepared for installation at Yemilab, a new underground laboratory in Korea, following 6.4 years of operation at the Yangyang Underground Laboratory. The COSINE-100 experiment aimed to investigate the annual modulation signals reported by the DAMA/LIBRA but observed a null result, revea...

For over 25 years, the DAMA/LIBRA collaboration has claimed to observe an annual modulation signal, suggesting the existence of dark matter interactions. However, no other experiments have replicated their result using different detector materials. To address this puzzle, the COSINE-100 collaboration conducted a model-independent test using 106 kg...

COSINE-100 is a direct dark matter search experiment, with the primary goal of testing the annual modulation signal observed by DAMA/LIBRA, using the same target material, NaI(Tl). In previous analyses, we achieved the same 1 keV energy threshold used in the DAMA/LIBRA's analysis that reported an annual modulation signal with 11.6$\sigma$ significa...

COSINE-100 aims to conclusively test the claimed dark matter annual modulation signal detected by DAMA/LIBRA collaboration. DAMA/LIBRA has released updated analysis results by lowering the energy threshold to 0.75 keV through various upgrades. They have consistently claimed to have observed the annual modulation. In COSINE-100, it is crucial to low...

The Yangsan fault is the most prominent NNE-SSW−striking active right-lateral strike-slip fault crossing the Korean Peninsula, with a continuous trace of ∼200 km. It can likely generate large earthquakes; however, the paleoseismic information on slip per event, slip rate, and timing of past ruptures along this fault remains sparse. To explore these...

We report new results from the Neutrino Elastic Scattering Observation with NaI (NEON) experiment in the search for light dark matter (LDM) using 2,636 kg$\cdot$days of NaI(Tl) exposure. The experiment employs an array of NaI(Tl) crystals with a total mass of 16.7 kg, located 23.7 meters away from a 2.8 GW thermal power nuclear reactor. We investig...

The AMoRE collaboration searches for neutrinoless double beta decay of $^{100}$Mo using molybdate scintillating crystals via low temperature thermal calorimetric detection. The early phases of the experiment, AMoRE-pilot and AMoRE-I, have demonstrated competitive discovery potential. Presently, the AMoRE-II experiment, featuring a large detector ar...

AMoRE searches for the signature of neutrinoless double beta decay of $^{100}$Mo with a 100 kg sample of enriched $^{100}$Mo. Scintillating molybdate crystals coupled with a metallic magnetic calorimeter operate at milli-Kelvin temperatures to measure the energy of electrons emitted in the decay. As a demonstration of the full-scale AMoRE, we condu...

The detection of weak features in spectra remains a challenge. Differentiation remains a standard method, but maximum-entropy filters provide an alternative. Using dielectric-function data for MoSe2 as a test case, we compare the capabilities of two maximum-entropy filters, the original Burg version and its corrected offshoot, to detect the biexcit...

AMoRE-II aims to search for neutrinoless double beta decay with an array of 423 Li$_2$$^{100}$MoO$_4$ crystals operating in the cryogenic system as the main phase of the Advanced Molybdenum-based Rare process Experiment (AMoRE). AMoRE has been planned to operate in three phases: AMoRE-pilot, AMoRE-I, and AMoRE-II. AMoRE-II is currently being instal...

Monolayer materials typically display intriguing temperature-dependent dielectric and optical properties, which are crucial for improving the structure and functionality of associated devices. Due to its unique photoelectric capabilities, monolayer WSe2 has recently received a lot of attention in the fields of atomically thin electronics and optoel...

The AMoRE-II experiment will search for the 0]ββ decay of 100 Mo nuclei using molybdate crystal scintillators, operating at milli-Kelvin (mK) temperatures, with a total of 80 kg of 100 Mo. The background goal for the experiment is 10-4 counts/ keV/kg/year in the region of interest around the 0]ββ decay Q-value of 3,034 keV. To achieve this level, t...

We present the development of a dual-detector system designed for investigating the spectral shape of forbidden non-unique beta decays. Two PbMoO4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}...

We report the temperature dependences of the dielectric function ε = ε1 + iε2 and critical point (CP) energies of the uniaxial crystal GaSe in the spectral energy region from 0.74 to 6.42 eV and at temperatures from 27 to 300 K using spectroscopic ellipsometry. The fundamental bandgap and strong exciton effect near 2.1 eV are detected only in the c...

We present a comprehensive study of the nonproportionality of NaI(Tl) scintillation detectors within the context of dark matter search experiments. Our investigation, which integrates COSINE-100 data with supplementary $$\gamma $$ γ spectroscopy, measures light yields across diverse energy levels from full-energy $$\gamma $$ γ peaks produced by the...

Since α-SnS has optically strong anisotropic characteristics, a simple method to determine its crystal orientation is strongly needed in device engineering. We report the parameter values of the Tauc–Lorentz model (TL) which can be used to determine the dielectric function (\(\varepsilon = \varepsilon_{1} + i\varepsilon_{2}\)) of α-SnS in the 1–5 e...

The natural barrier of radioactive waste disposal site should permanently isolate radionuclides from human environments for a geologically long-term period. Therefore, it is necessary not only to reconstruct the past-to-present evolution of the bedrock, but also to predict its future evolution. An analytic methodology to assess the geological evolu...

The macroseismic intensity of the February 6, 2012, Negros Oriental earthquake (MW 6.7), which affected the islands of Negros and Cebu, central Philippines, has been reassessed in this study using the Environmental Seismic Intensity Scale (ESI-2007). This earthquake caused a ∼75-km-long surface rupture along a previously unmapped fault and resulted...

The seismic shaking observed around Delhi and the surrounding region due to near-field and far-field earthquakes is a matter of concern for the seismic safety of the national capital of India, as well as the historical monuments of the region. Historical seismicity indicates that the Delhi region has been affected by several damaging earthquakes or...

Monolayer materials typically display intriguing temperature-dependent dielectric and optical properties, which are crucial for improving the structure and functionality of associated devices. Due to its unique photoelectric capabilities, monolayer WSe 2 has recently received a lot of attention in the fields of atomically thin electronics and optoe...

We present the development of a dual-detector system designed for investigating the spectral shape of forbidden non-unique beta decays. Two PbMoO 4 scintillating crystals were carefully prepared for heat and light detection at milli-Kelvin (mK) temperatures. Notably, one crystal was synthesized using archaeological lead, while the other was compose...

We report the results of a search for inelastic scattering of weakly interacting massive particles (WIMPs) off I127 nuclei using NaI(Tl) crystals with a data exposure of 97.7 kg·years from the COSINE-100 experiment. The signature of inelastic WIMP−I127 scattering is a nuclear recoil accompanied by a 57.6 keV γ-ray from the prompt deexcitation, prod...

We search for energetic electron recoil signals induced by boosted dark matter (BDM) from the galactic center using the COSINE-100 array of NaI(Tl) crystal detectors at the Yangyang Underground Laboratory. The signal would be an excess of events with energies above 4 MeV over the well-understood background. Because no excess of events are observed...

Various weakly interacting massive particle (WIMP) dark matter searches using the full data set of XMASS-I, a single-phase liquid xenon detector, are reported in this paper. Stable XMASS-I data taking accumulated a total live time of 1590.9 days between November 20, 2013 and February 1, 2019 with an analysis threshold of 1.0 keVee. In the latter ha...

We present results of a search for bosonic super-weakly interacting massive particles (BSW) as keV scale dark matter candidates that is based on an exposure of 97.7 kg·year from the COSINE experiment. In this search, we employ, for the first time, Compton-like as well as absorption processes for pseudoscalar and vector BSWs. No evidence for BSWs is...

Two recent moderate earthquakes in South Korea, the 2016 MW 5.5 Gyeongju earthquake and 2017 MW 5.4 Pohang earthquake, caused damages to modern residential buildings. These events occurred with almost the same magnitude and duration in the same seismotectonic environment but exhibited remarkably different focal depths, faulting types, surface defor...

We report the results of a search for inelastic scattering of weakly interacting massive particles (WIMPs) off $^{127}$I nuclei using NaI(Tl) crystals with a data exposure of 97.7\,kg$\cdot$years from the COSINE-100 experiment. The signature of inelastic WIMP-$^{127}$I scattering is a nuclear recoil accompanied by a 57.6\,keV $\gamma$-ray from the...

We present results from a search for solar bosonic dark matter using the annual modulation method with the COSINE-100 experiment. The results were interpreted considering three dark sector bosons models: solar dark photons, Dine-Fischler-Srednicki-Zhitnisky (DFSZ) and Kim-Shifman-Vainshtein-Zakharov (KSVZ) solar axions, and Kaluza-Klein solar axion...

Integration of geological and geophysical data is essential to elucidate the configuration and geometry of surface and subsurface structures, as well as their long-term evolution. The NNW–SSE-striking incised valley and parallel mountain range in the southeastern margin of the Korean Peninsula, extending 50 km from Gyeongju to Ulsan cities, are tog...

We search for energetic electron recoil signals induced by boosted dark matter (BDM) from the galactic center using the COSINE-100 array of NaI(Tl) crystal detectors at the Yangyang Underground Laboratory. The signal would be an excess of events with energies above 4MeV over the well-understood background. Because no excess of events are observed i...

We present results of a search for bosonic super-weakly interacting massive particles (BSW) as keV scale dark matter candidates that is based on an exposure of 97.7 kg$\cdot$year from the COSINE experiment. In this search, we employ, for the first time, Compton-like as well as absorption processes for pseudoscalar and vector BSWs. No evidence for B...

Neutrino elastic scattering observation with NaI (NEON) is an experiment designed to detect neutrino-nucleus coherent scattering using reactor electron antineutrinos. NEON is based on an array of six NaI(Tl) crystals with a total mass of 13.3 kg, located at the tendon gallery that is 23.7 m away from a reactor core with a thermal power of 2.8 GW in...

The CUP array of germanium (CAGe) is an array of fourteen high-purity germanium (HPGe) detectors. The detection efficiency of full-energy-peak emitted from the various samples assayed on the CAGe was calculated using the Monte Carlo simulation toolkit GEANT4. If the dead layer on the surface of the crystal is treated in the simulation as a continuo...

A convolutional neural network (CNN) architecture is developed to improve the pulse shape discrimination (PSD) power of the gadolinium-loaded organic liquid scintillation detector to reduce the fast neutron background in the inverse beta decay candidate events of the NEOS-II data. A power spectrum of an event is constructed using a fast Fourier tra...

The 28th September 2018 Sulawesi Supershear earthquake (MW 7.5) was one of the deadliest earthquakes in the recent history of Indonesia causing ~4000 causalities. The earthquake caused a ~ 177 km long surface rupture along the Palu-Karo fault. Apart from surface rupture, the earthquake caused extensive earthquake environmental effects (EEEs) around...

We present results from a search for solar bosonic dark matter using the annual modulation method with the COSINE-100 experiment. The results were interpreted considering three dark sector bosons models: solar dark photon; DFSZ and KSVZ solar axion; and Kaluza-Klein solar axion. No modulation signal that is compatible with the expected from the mod...

The COSINE-100 experiment has been operating with 106 kg of low-background NaI(Tl) detectors to test the results from the DAMA/LIBRA experiment, which claims to have observed dark matter. However, since the background of the NaI(Tl) crystals used in the COSINE-100 experiment is 2–3 times higher than that in the DAMA detectors, no conclusion regardi...

The Advanced Mo-based Rare process Experiment (AMoRE)-Pilot experiment is an initial phase of the AMoRE search for neutrinoless double beta decay of $$^{100}$$ 100 Mo, with the purpose of investigating the level and sources of backgrounds. Searches for neutrinoless double beta decay generally require ultimately low backgrounds. Surface $$\alpha $$...

A convolutional neural network (CNN) architecture is developed to improve the pulse shape discrimination (PSD) power of the gadolinium-loaded organic liquid scintillation detector to reduce the fast neutron background in the inverse beta decay candidate events of the NEOS-II data. A power spectrum of an event is constructed using a fast Fourier tra...

Various WIMP dark matter searches using the full data set of XMASS-I, a single-phase liquid xenon detector, are reported in this paper. Stable XMASS-I data taking accumulated a total live time of 1590.9 days between November 20, 2013 and February 1, 2019 with an analysis threshold of ${\rm 1.0\,keV_{ee}}$. In the latter half of data taking a lower...

AMoRE is an international project to search for the neutrinoless double beta decay of $^{100}$Mo using a detection technology consisting of magnetic microcalorimeters (MMCs) and molybdenum-based scintillating crystals. Data collection has begun for the current AMORE-I phase of the project, an upgrade from the previous pilot phase. AMoRE-I employs t...

The second phase of the Advanced Mo-based Rare process Experiment (AMoRE-II) searches for a neutrino-less double-beta decay of ¹⁰⁰ Mo. A background level in the region of interest of 3034 ± 10 keV is required to be lower than 10 ⁻⁴ count/(keV kg year). Neutrons can generate background signals by gamma-ray emitting reactions with AMoRE-II detector m...

AMoRE is an international project to search for the neutrinoless double beta decay of 100Mo\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{100}\hbox {Mo}$$\end{docume...

For nearly 50 years the Burg/Andersen (BA) maximum‐entropy deconvolution procedure has been used to sharpen, and therefore accentuate, weak features in spectra, optical and otherwise. We show that the BA procedure can be further enhanced to yield even sharper features. Using this approach we establish the existence of the biexciton in ellipsometric...

The macroseismic intensity of the February 6, 2018, Mw 6.4, Hualien earthquake, which caused extensive damage around the Hualien area of eastern Taiwan is reassessed using the Environmental Seismic Intensity (ESI-07) scale. We compiled data on earthquake environmental effects (EEEs) caused by the 2018 Hualien earthquake, which includes surface rupt...

COSINE-100 is a direct detection dark matter experiment that aims to test DAMA/LIBRA’s claim of dark matter discovery by searching for a dark-matter-induced annual modulation signal with NaI(Tl) detectors. We present new constraints on the annual modulation signal from a dataset with a 2.82 yr livetime utilizing an active mass of 61.3 kg for a tota...

We present a background model for dark matter searches using an array of NaI(Tl) crystals in the COSINE-100 experiment that is located in the Yangyang underground laboratory. The model includes background contributions from both internal and external sources, including cosmogenic radionuclides and surface 210Pb contamination. To build the model in...

The AMoRE collaboration is preparing for the AMoRE-II experiment that will probe neutrinoless double beta decay with 100 kg of ¹⁰⁰Mo isotope. The ¹⁰⁰Mo nuclide will be mainly in the form of lithium molybdate crystals that are instrumented with metallic magnetic calorimeters (MMC), which detect the phonon excitations produced by electrons from neutr...

The advanced Mo-based rare process experiment (AMoRE) is an international project searching for the neutrinoless double beta (0νββ) decay of 100Mo using low-temperature calorimetric detection of heat and light signals based on magnetic microcalorimeter (MMC) readouts. Li2MoO4 crystals have been considered as the main target crystals for the second...

The DAMA/LIBRA collaboration has reported the observation of an annual modulation in the event rate that has been attributed to dark matter interactions over the last two decades. However, even though tremendous efforts to detect similar dark matter interactions were pursued, no definitive evidence has been observed to corroborate the DAMA/LIBRA si...

In the last several years, considerable progress has been made in reducing or eliminating noise in ellipsometric spectra, including the development of algorithms for eliminating endpoint-discontinuity artifacts, a reciprocal-space expression for quantifying the effectiveness of linear filters, and the corrected maximum-entropy (CME) approach for el...

The AMoRE collaboration is preparing for the second phase of the experiment, AMoRE-II, which will exploit a 100 kg of ¹⁰⁰ Mo isotopes to search for neutrinoless double beta decay from the isotope. Most of the ¹⁰⁰ Mo isotopes will be contained in the lithium molybdate (Li 2 MoO 4 ) crystals, which will act as absorbers of cryogenic calorimeters coup...

A search for the neutrinoless quadruple beta decay of ¹³⁶Xe was conducted with the liquid-xenon detector XMASS-I using 327 kg ×800.0 days of the exposure. The pulse shape discrimination based on the scintillation decay time constant which distinguishes γ-rays including the signal and β-rays was used to enhance the search sensitivity. No significant...

We present a nearly reactor model independent search for sterile neutrino oscillation using 2 509 days of RENO near detector data and 180 days of NEOS data. The reactor related systematic uncertainties are significantly suppressed as both detectors are located at the same reactor complex of Hanbit Nuclear Power Plant. The search is performed by ele...

Gasado Island, on the southwestern Korean Peninsula, comprises c. 50 Ma volcanic rocks that are cut by faults and fractures hosting low-sulfidation epithermal Au-Ag mineralization. In this study, we examined the relationship between the fault-fracture networks and auriferous vein systems to better understand the role of brittle structures in contro...

A search for the neutrinoless quadruple beta decay of $^{136}$Xe was conducted with the liquid-xenon detector XMASS-I using $\rm 327\; kg \times 800.0 \; days$ of the exposure. The pulse shape discrimination based on the scintillation decay time constant which distinguishes $\gamma$-rays including the signal and $\beta$-rays was used to enhance the...

In seismic hazard assessment, subsurface geophysical surveying has gained popularity in recent years towards fault mapping and determining seismic deformation parameters such as fault offset, recurrence, and depth of fault, locating proper trench sites based on the subsurface information. In the present study, electrical resistivity tomography (ERT...

Neutrino Elastic scattering Observation with NaI (NEON) is an experiment designed to detect neutrino-nucleus coherent scattering using reactor electron antineutrinos. NEON is based on an array of six NaI(Tl) crystals with a total mass of 13.3 kg, located at the tendon gallery that is 24 m away from a reactor core with a thermal power of 2.8 GW in t...